I dont think La Liga is anywhere near as competitive as the Premier league. Its not the 2 horse race it has been between Real and Barca previously, In the last decade Atletico have really come into the equation but the bottom half of La Liga isnt as strong as the bottom half of the premier league imo. I think the top 6-8 of La Liga and the Premier league are probably similar in standards.
Pele you have a point about, but not Maradona, he played most of his career outside Argentina. He played in top flight Spain with Barcelona and Sevilla, he played in Serie A with Napoli, who were a very ordinary side until he got there, and he turned them not only into title challengers but winners. He also won a world cup with a pretty average Argentina team and like at Napoli, he was the driving force behind it.
Hard to be over critical of Pele though really as when he was coming through players didnt tend to move abroad like they do now. In terms of World cup players, imo he is the GOAT. Won and dominated in 3 world cups, and probably would have in a 4th in 1966 if he didnt get brutally kicked from pillar to post. I dont think anyone has come close to him in that respect.
Messi, as much as it pains me to say it just isnt as good as Maradona. Maradona has proved he can turn an ordinary team into a great one, Messi, like Ronaldo, has just made a great side better. I think this Argentina side is a lot better than you are giving them credit for as well. They have a lot of talent all over and are a very strong side. I dont think they have performed well, Messi hasnt even had a great tournament but you would expect them to be capable of challenging with the talent they have.